Planning an Invasive Surgery on My Ankle: Need Advice

I’m about to plan an invasive surgery on my ankle in the next month or so. I had surgery for the first time back in 2015 when I was a teenager, but new problems have emerged. I have a cyst in my talus and I’m going to have a bone graft from my knee to replace the unhealthy bone and hyaline cartilage with the healthy sample from my knee. They’re also going to need to slice through my tibia to reach the affected site, and then they’ll need to put screws in my tibia to repair it. Has anyone here gone through any similar procedures or know anything about it? I’m a little nervous and worried about the possible risks of opening up the site of a healthy joint to get a couple chunks of donor bone.